Brown chops in a skillet. Place them in a baking dish. Sprinkle onion, peppers and mushrooms in the same pan. Add the tomato sauce and oregano. Add salt and pepper. Bake 325 degree oven for 1 1/2 hours. Remove from oven. Place a scoop of rice over each chop and baste the rice with the sauce. Place chops back in the oven and cook for 30 more minutes. Serves 8.